What it is and what it does
The Siemens 3VA1112-6MH36-0BA0 is a 3-pole IEC frame 160 circuit breaker rated 125 A with a high breaking capacity of 70 kA at 415 V AC (class H). It is configured for starter protection with a TM120M thermal-magnetic release, meaning the thermal element is sized for motor starting profiles while the magnetic short-circuit pickup is adjustable from 5 to 15 times In. The unit includes an undervoltage release (UVR) coil at 24 V DC and uses clamp (box lug) terminals.
Key ratings and what they mean for fit
The 70 kA Icu at 415 V is the ultimate short-circuit breaking capacity — the breaker can safely interrupt a fault current up to that level once without needing replacement. For motor starting duty, the TM120M thermal element provides inverse-time overload protection matched to a 125 A motor full-load current; the magnetic pickup range (5–15× In = 625–1875 A) covers locked-rotor and bolted-fault conditions. The UVR coil at 24 V DC trips the breaker when control voltage drops, standard for emergency-stop or undervoltage protection schemes.
Where it is used
This breaker is designed for motor branch circuits in industrial control panels — typically feeding a motor starter or contactor combination. The 3VA1 frame mounts on a DIN rail or panel baseplate and accepts clamp terminals for copper or aluminum conductors up to the rated cross-section. The UVR coil connects to a 24 V DC safety circuit; verify polarity and that the coil draw does not exceed the control transformer rating.